A top U.S. diplomat says Washington is "concerned" about statements made last week by Serbian officials in northern Kosovo regarding the upcoming December 12 parliamentary elections.

Local leaders have warned that the establishment of polling stations in four Serb-majority municipalities in the north would constitute a provocation.

Dragisa Milovic, the head of the Zvecan municipality near the ethnically divided city of Mitrovica, said the opening of voting stations in predominantly Serb areas would be "unacceptable."

At a hearing of the U.S. Helsinki Commission, U.S. Deputy Assistant Secretary for European and Eurasian Affairs Tom Countryman said the threats "have had their desired effect."

"These threats from last week have had their desired effect, intimidating voters who wish to participate in any way in the public life of the Republic of Kosovo," Countryman said. "They are credible threats because they occur in the context of a series of violent incidents directed against Serbs in the north [of Kosovo] who do cooperate."

Kosovo's north remains under the unofficial control of Belgrade-backed Serb leaders who defy Kosovo's 2008 unilateral declaration of independence and the EU's rule of law mission in the former Serbian province.

Belgrade has also decided not to support Kosovar Serb participation in Kosovo's upcoming elections, which will be its first since declaring independence from Serbia in February 2008.

The elections are being watched by the international community and are seen as a test of Pristina's ability to conduct fair elections and integrate the Serbian community, most of which has fiercely opposed Kosovo's separation from Serbia.

Countryman said the United States "expects and encourages the government of Serbia to do everything possible to cool the atmosphere and prevent any such violence from occurring."

A Bosnian Muslim who was part of a team in charge of organizing the weekend poll in northern Kosovo was shot dead in the region on December 8. The EU condemned the violence.